1. Field of the Invention
The present invention relates to locking devices and, more particularly, to card operable magnetic locks of the type having magnetic locking tumblers adapted to be displaced by a coded magnetic card.
2. Description of the Prior Art
Card operable magnetic locks have been widely used for operating parking lot gates, turnstiles, doors, and other barriers in various types of access control systems. As typified by U.S. Pat. No. 3,271,983, such locks comprise a core which carries a plurality of slidable magnetic tumbler pins arranged in a predetermined pattern and biased into locking openings of one or more lock plates to prevent relative movement of the lock plates. A magnetically coded card having magnetic areas or elements arranged in a pattern corresponding to the tumbler pins is inserted into the lock so as to displace the tumbler pins axially from the openings in the lock plate to permit relative movement of the core or actuate a switch.
Such card operable magnetic locks permit the use of relatively low cost cards in place of conventional keys and provide high security due to the numerous magnetic codes that can be utilized. However, such prior art devices are relatively expensive, cannot be easily reprogrammed to new magnetic codes, and usually require electrical actuation of the barrier itself. Accordingly, card operable magnetic devices are not generally used in lock applications such as storage cabinets and storage lockers. Previous attempts to provide reprogramming features within a card operable magnetic device, as disclosed in U.S. Pat. No. 3,444,722, require the addition of movable code combination members which further increase complexity and expense. Locks having rotary magnetic tumbler elements, as disclosed in U.S. Pat. No. 3,633,393, have not been used with cards in place of conventional keys and have not been easily reprogrammable.
Accordingly, it is a general object of the present invention to provide an improved card operable magnetic lock.
It is another object of the present invention to provide a mechanism of the above type in which the magnetic code can be easily changed.
It is a further object of the present invention to provide a magnetically operated lock mechanism which can be used without electrical assistance to provide an access control for storage cabinets, lockers, doors, and similar devices.
It is a further object of the present invention to provide a magnetically operated lock mechanism of the above type which is simple in construction and economical to produce.